Purpose

Empty follicle syndrome (EFS) refers to the inability to obtain mature oocytes after appropriate ovarian stimulation during the process of in vitro fertilization (IVF). However, the specific cause and mechanism of action underlying EFS remain to be further explored. Herein we aimed to investigate the clinical and genetic characteristics of EFS.

Methods

After data were collected in an infertile family, we performed whole-exome sequencing (WES) on the patient and confirmed the pathogenic mutations through Sanger sequencing. Western immunoblotting, immunofluorescence staining, and minigene assay were further used to investigate the negative effects of these mutations.

Results

Absence of oocytes was observed over 2 cycles of IVF in the patient, and we evaluated the novel compound heterozygous mutations c.2T>A (p. M1K) and c.1112+1G>T of the zona pellucida glycoprotein 1 gene (ZP1, MIM# 195000) by WES. For the family under study, EFS was classified as an autosomal recessive inheritance pattern. The results of western blotting and immunofluorescence staining analyses confirmed that the missense mutation of c.2T>A [p. M1K] resulted in almost missing protein production. Additionally, using a minigene assay, we demonstrated the deleterious effect on the ZP1 gene of the splice site mutation c.1112+1G>T, which caused truncation of ZP1 protein.

Conclusions

The compound heterozygous mutations of ZP1 gene identified in this study by genetic and functional experiments constituted a novel genetic cause of EFS, and further study will expand its use in the clinical and molecular diagnoses of EFS.

中文翻译：

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在患有空卵泡综合征的不育女性中发现的 ZP1 中新型双等位基因功能丧失变体。

目的

空卵泡综合征（EFS）是指在体外受精（IVF）过程中，经过适当的卵巢刺激后，无法获得成熟的卵母细胞。然而，EFS 的具体原因和作用机制仍有待进一步探索。在此，我们旨在研究 EFS 的临床和遗传特征。

方法

在一个不育家庭中收集数据后，我们对患者进行了全外显子组测序（WES），并通过 Sanger 测序确认了致病突变。进一步使用蛋白质免疫印迹、免疫荧光染色和小基因测定来研究这些突变的负面影响。

结果

在患者的 2 个 IVF 周期中观察到没有卵母细胞，我们评估了透明带糖蛋白 1 基因 (ZP1, MIM# 195000）由 WES。对于所研究的家庭，EFS 被归类为常染色体隐性遗传模式。Western印迹和免疫荧光染色分析结果证实c.2T>A的错义突变[p. M1K]导致几乎没有蛋白质生产。此外，我们使用小基因分析证明了剪接位点突变 c.1112+1G>T对ZP1基因的有害影响，这会导致 ZP1 蛋白的截断。

结论

本研究通过遗传和功能实验鉴定的ZP1基因复合杂合突变构成了EFS的新遗传原因，进一步研究将扩大其在EFS的临床和分子诊断中的应用。